THE PIPER ALPHA, owned by Occidental Oil, was the largest and oldest oil platform in the North Sea oil field, located 120 miles (193 kilometers) off the coast of Scotland, according to BBC News. It was built in 1975 and produced about 300,000 barrels of oil a day.

On a night in 1988, though, a series of explosions, followed by a devastating fire, destroyed the platform. Of the crew of 226, 165 died. Two members of the rescue vessel Sandhaven also perished. It was the worst off-shore oil disaster in history.

Around noon on July 6, the safety valve on one of the platform’s two condensate pumps, which prepared natural gas for transport, was taken out of service for maintenance and temporarily replaced with a blind flange, or metal cover. The flange was hand-tightened, and the engineer filled out a permit saying that the pump was not to be started under any circumstances. But he neglected to tell the night-shift engineer personally, and the permit was left in the control center, where it disappeared.

At 9:45 p.m. that night, the second condensate pump failed, and the unsuspecting manager, with just minutes to bring the operation back on line before the entire power supply to the platform failed, started the out-of-service pump. Ten minutes later, the valve overpressured, triggering gas alarms.

“All the alarms are coming in, and every time I [tried] to stop one, there’s another one,” said Geoff Bollands, the control room operator that night, according to the BBC documentary Fire in the Night.

The first explosion occurred at 9:55 p.m., badly damaging the control room, which was abandoned shortly after 10 p.m. A gas line burst at 10:20 p.m., spewing tons of gas that immediately triggered an immense explosion, followed by an enormous fire that engulfed the platform. By 12:45 a.m. on July 7, most of Piper Alpha had collapsed into the North Sea. The fire continued until three weeks later, when a team led by Texas oil well firefighter Red Adair brought it under control.

At a ceremony on the 25th anniversary of the disaster, the Rev. Gordon Craig, the chaplain to the Scottish oil and gas industry, noted that the Piper Alpha tragedy led to more than 100 changes in safety practices.

“Sadly, it took the lives of 167 men for it to learn some of the lessons,” he said, according to BBC News. “But the safety of the North Sea has improved beyond all recognition.”